1. Field of the Invention
The invention relates to a transmission mechanism for a dual-shaft hinge, and more particularly to a transmission mechanism using helical gear set to synchronize rotation of two shafts of the hinge.
2. Description of the Related Art
It is a popular design for a display of a laptop detachable from its base. The detached display can be used as a tablet. When the display is joined to the base, is can be rotated to an arbitrary angle with respect to the base by a dual-shaft hinge. By the dual-shaft hinge, the display can even be flipped (rotated 360°) to overlap the base to serve as a tablet.
A conventional dual-shaft hinge includes a first shaft rotated along with the display and a second shaft rotated along with the mainframe. However, when the dual-display is rotated to a large angle or flip to overlap the mainframe by the dual shaft hinge, the display is rotated by one shaft to a specific angle first, and rotated to the intended angle by the other shaft. The entire rotation mechanism is so complicated that it causes high cost in manufacture and assembly, and also causes slow and not smooth in flip operation. It is inconvenient for the display flipped 360° by rotated to a predetermined angle by one shaft and then rotated by the other shaft.
The rotation of the display for a large angle is accomplished by the dual-shaft hinge. The conventional dual-shaft hinge is often equipped with complicated transmission mechanism which occupies large space and is not conducive to miniaturization of the laptop.